I have been using x2go for many months now,
client (Debian amd64 4.0.1.1-1),
x2goserver (Debian amd64 4.0.1.6-0)
.. is the current version, but it's been the same ever since.
I use it in the "single application" mode, starting only xfce4-terminal and all the other windows are spawned from that terminal.
What happens is that very often (I would say 20-30% of the cases -- it's not deterministic), I would resume a session, it is "resumed", but no windows appear. Nothing helps, suspending and resuming does not work. The only thing to do is to terminate the session and start anew. It's quite annoying:) I wonder if anyone has this issue or am I doing something wrong / non-standard? How can I debug this?
BTW, I use awesome wm now, but the same was happening to me on xfce, too